The present invention pertains to a method for providing an adaptive delay after impact in projectiles.
In the design of projectiles fuzes for impact functiions, it is often desirable to provide for detonation of the projecticle within the target, such as an urban structure, rather than at the instant of first contact. This can be accomplisyed in myriad ways, ranging from a simple non-varying delay time between first impact and detonation to void sensing to determining detonation. Void sensors must have sufficient damping so that structural ringing does not activate them early. This results in a slow response time that makes void sensors unable to adapt to high and low velocity impacts. Similarly, fixed time delay devices of the prior art are not capable of adjusting between the varying velocities and varying sizes, that is caliber and associated length, of projectiles. In U.S. Pat. No. 4,580,498 entitled "Fuze Actuating System Having a Variable Impact Delay", issued Apr. 8, 1986, a variable impact delay has been devised which employs a set time delay after impact for a projectile with a given velocity. The delay is updated dependent upon the time of flight of the projectile. While this accomplishes the basic requirements, size and initial velocity of projectiles must remain constant for its proper functioning. It cannot be used in projectiles that are capable of varied initial velocities such as is possible in artillery shells.